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[PATCH] Coverity: safe umask before mkstemp #13773
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From @jhiUse safe umask (0600) before mkstemp. Modern glibcs use a safe umask, Attached. |
From @jhi0001-Fix-for-Coverity-perl5-CID-29068.patchFrom c9ec3abfc6deeaf1683f26120b9de7f56580d1e5 Mon Sep 17 00:00:00 2001
From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Thu, 24 Apr 2014 12:23:18 -0400
Subject: [PATCH] Fix for Coverity perl5 CID 29068: Insecure temporary file
(SECURE_TEMP) secure_temp: Calling mkstemp() without securely setting umask
first.
The umask used for mkstemp should be secure, but umask 0600 has been
the required umask only since POSIX.1-2008. In glibc 2.06 and earlier
the default was 0666, which is not secure. And no explicit knowledge
of how well non-glibc platforms implement mkstemp. Better err on the
side security, so set the umask temporarily to 0600, and then restore it.
---
perl.c | 2 ++
perlio.c | 2 ++
2 files changed, 4 insertions(+)
diff --git a/perl.c b/perl.c
index 27d0d9e..f5007f7 100644
--- a/perl.c
+++ b/perl.c
@@ -3763,7 +3763,9 @@ S_open_script(pTHX_ const char *scriptname, bool dosearch, bool *suidscript)
const char * const err = "Failed to create a fake bit bucket";
if (strEQ(scriptname, BIT_BUCKET)) {
#ifdef HAS_MKSTEMP /* Hopefully mkstemp() is safe here. */
+ int old_umask = umask(0600);
int tmpfd = mkstemp(tmpname);
+ umask(old_umask);
if (tmpfd > -1) {
scriptname = tmpname;
close(tmpfd);
diff --git a/perlio.c b/perlio.c
index 0ae0a43..9b466b6 100644
--- a/perlio.c
+++ b/perlio.c
@@ -4961,6 +4961,7 @@ PerlIO_tmpfile(void)
char tempname[] = "/tmp/PerlIO_XXXXXX";
const char * const tmpdir = TAINTING_get ? NULL : PerlEnv_getenv("TMPDIR");
SV * sv = NULL;
+ int old_umask = umask(0600);
/*
* I have no idea how portable mkstemp() is ... NI-S
*/
@@ -4982,6 +4983,7 @@ PerlIO_tmpfile(void)
sv_catpv(sv, tempname + 4);
fd = mkstemp(SvPVX(sv));
}
+ umask(old_umask);
if (fd >= 0) {
f = PerlIO_fdopen(fd, "w+");
if (f)
--
1.9.2
|
From @tonycozOn Sat Apr 26 12:56:06 2014, jhi wrote:
While I think the patch is good, threaded code that uses C<< open my $fh, "+>", undef >> might see some intermittent unexpected permissions on files created in other threads. Unfortunately umask() updates the mask for the whole process and there's no thread-local variant, so I don't see a thread-safe solution. Added to the 5.21.1 list. Tony |
The RT System itself - Status changed from 'new' to 'open' |
@tsee - Status changed from 'open' to 'resolved' |
Migrated from rt.perl.org#121742 (status was 'resolved')
Searchable as RT121742$
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